1. Field of the Invention
The invention relates to a flexible container, in practice for single use for sterile applications, suitable to be used in particular for transporting products or small items such as piston joints or bottle stoppers as well as a process for manufacturing such a flexible container.
2. Description of the Related Art
In accordance with the document FR-2 721 289 (or EP-0 688 020, or U.S. Pat. No. 5,853,207), a device with a sealed junction between two chambers isolated from an external environment as well as a disposable chamber that is suitable for being used in such a device are known. Such a disposable chamber is basically mobile, while the other chamber can be a larger and heavier chamber, for example a sterilization chamber or a reactor. These chambers are each equipped with an opening that is equipped with a flange that is normally sealed by a door, and the sealed junction between these chambers uses the joint maneuvering of the two doors. These two doors are preferably for single use.
For practical reasons, these disposable chambers, also called disposable containers, generally consist of a combination of a rigid door (or cover) and a pocket (or bag) made of flexible plastic material, most often transparent. Such disposable containers can be used to transport all types of products, liquids, solids or powders to larger chambers (and even from the latter).
When these disposable containers are designed to transport products or small items, they can also comprise a second door, of the same type as the first, so as to allow the input of products or items via one of the doors, and the output of products or items via the other one of these doors.
If necessary, such containers make possible the application of a treatment with products or items that are contained therein, for example a sterilization treatment. This sterilization can be carried out by steam, by gamma-radiation, or by beta-radiation. Such a sterilization can be provided in particular when the containers are used for transporting small items, such as piston joints, stoppers, needle cases, etc., which are designed to be in direct contact with injectable products.
The requirements that relate to such containers first dealt with their strength, their sterilization capability (with steam or radiation), and their cleanliness. There were virtually no tests on the flexible containers (or packets).
Little by little, the requirements have been reinforced, and monitoring is henceforth conducted in an increasingly rigorous manner on these flexible containers. Thus, from now on, it may be possible to initiate monitoring on the particulate and/or endotoxin level. Furthermore, the generally relative idea of sealing (relative to gases, to water vapor, etc.) has gained importance.
It is thus, for example, that the users now desire to initiate monitoring of the integrity of films that constitute the flexible portion of the containers. Actually, it became desirable that the films not solely constitute barriers to microorganisms but also barriers to water vapor (in particular in the case of lyophilizates), etc. It should be noted that, by way of example, this monitoring is not satisfied when the films are made of a material that is based on fine high-density polyethylene fibers known under the trademark “TYVEK”® of DUPONT, making possible steam sterilizations.
Furthermore, the monitoring done at the manufacturing stages is, moreover, rigorous. Thus, in particular, the seams are no longer simply monitored visually, but also undergo sealing tests, in methylene blue, for example, pressure resistance tests, elongation tests, etc.
This is why the manufacturers of plastic films are all made to work—for the manufacturing of sheets or casings for containers—at cleanliness levels that continue to improve. Thus, it is easy to define the manufacturing, starting from an extruded casing, of simple flexible bags whose inside volume is specific: after the tube is extruded, it is sufficient to keep the casing flat and to weld it without having to manipulate it or to open it partway.
For the manufacturing of more elaborate containers, comprising access doors, such as disposable doors of the above-mentioned type, an effort is made to use the above-mentioned principle by adapting such doors to it while obtaining the same level of quality as with simple bags.
However, any intervention, whether it be human or not, is necessarily a source of contamination, reducing the quality of the casing in question. It follows therefrom that the assembling of one or more doors in a casing initially having a high level of cleanliness in principle involves a deterioration of this level of cleanliness.